The invention relates to nails with spreadable legs used to fasten various objects to ALC (autoclaved light-weight concrete) or concrete walls or blocks, and to a method for manufacturing the same.
FIGS. 4A and 4B show a conventional nail.
This nail 1 comprises two legs 2, 3 having trunk portions 4 and 5 which have a semicircular section and flat heads 6 and 7 at one end thereof. A protrusion 8 is formed on the trunk portion 4 of the leg 2 near its tip. Initially, the legs 2 and 3 are bound together by a washer 9 so that the head 7 of the leg 3 is located offset from the head 6 of the leg 2 and the flat opposed surfaces are in close contact with each other with the tip of the leg 3 not overlying the protrusion 8.
To fasten an object B to a concrete wall A using the nail 1, a starting hole is formed in the wall A, and with the nail inserted through the object B into the starting hole until the washer 9 abuts the object B, the leg 3 is driven in by striking its head 7. As the leg 3 is driven in, it is bent or spread while riding onto the protrusion 8 as shown in FIG. 4B. Once driven in as shown, the legs 2, 3 will spread and be rigidly retained in the wall with the object B fastened to the wall by the heads 6 and 7. If the wall is made of ALC, the nail 1 can be driven into the wall directly without forming a starting hole to fasten an object to the wall.
Heretofore, in order to provide the protrusion 8, both legs 2 and 3 were formed by casting in molds, or the leg 2 was formed by partially cutting a rod having a circular section to form the protrusion 8.
Casting requires expensive molds and a facility for melting a metal material. Thus casting is expensive, inefficient and low in mass-productivity.
On the other hand, when the leg 2 is formed by cutting out a round rod, loss of material will be a major problem because the cut-out portion has to be discarded. Cutting a material is troublesome and time-consuming.
An object of this invention is to provide a nail which can be manufactured at low cost without loss of material.
According to the present invention, there is provided a nail comprising two legs bound together by a washer, one of the legs having a protrusion such that when the other leg is driven, it will spread by riding on the protrusion, the one leg having a tip portion at one end thereof, a head at the other end thereof, and a semicircular trunk portion, the protrusion being disposed between the tip portion and the trunk portion.
Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which: